Nicotiana tabacum is a common domestic insect, with brown-black body color and usually white spots. This bug has a pair of tentacles and three pairs of feet, and its larvae will live in tobacco, tea, paper and other places. If this kind of bug appears at home, it may be because you bought tobacco or tea with tobacco beetles, or there is a damp and moldy place at home. Some measures can be taken, such as keeping the house clean and dry, sealing the place where tobacco, tea and other items are stored to prevent the emergence of this kind of insect.
Dermatophagoides nigricans usually have degenerated wings and usually appear at home in the form of larvae or adults. The insect body is changeable, but its characteristics are obvious, such as hard and black body. They often move in living rooms, storerooms, warehouses and other places, and breed faster. Although these bugs look annoying, they are not too harmful. If you are worried about the health of your family, you can take some measures to get rid of them, such as keeping your home clean and ventilated, using aerosol pesticides or using bait to trap them.
Please note that the above is only speculation. If in doubt, it is recommended to consult a professional entomologist or zoologist for more accurate information.